Moisture removal device for a steam turbine

ABSTRACT

A row of stationary blades of the steam turbine having interconnecting cavities in the base portions thereof to form an annular chamber which cooperates with inlet and outlet ports disposed adjacent the trailing edges of these blades and adjacent the casing and rotor respectively to remove water and steam from the stationary blades, to separate the water and steam, and to direct the steam toward an adjacent row of rotating blades and the water to a drain.

United States Patent v 1191 Fischer [54] MOISTURE REMOVAL DEVICE FOR ASTEAM TURBINE Y [75] Inventor: Frederick K. Fischer, Wawa, Pa. [73]Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa. [22] Filed: Oct. 28, 1971 211 Appl. No.: 193,345

52 US. Cl AIS/168, 415/010. 1 [51] Int. Cl. ..F0ld 25/32, FOld 15/00[58] Field of Search ..4l5/DIG. 1,121 A, 168

[56] References Cited UNITED STATES PATENTS 741,776 10/1903 Dodge..4l5/l68 2,lll,878 3/1938 Tongeren. ..4l5/l68 2,332,322 10/1943 Kraft..4l5/l68 2,362,831 11/1944 Kraft. ..4l5/l68 2,399,009 4/1946 Doran..415/l68 1/1967 Wood ..4l5/168 Primary Examiner-Henry F. RaduazoAttorney-A. T. Stratton et al.

ABSTRACT A row of stationary blades of the steam turbine havinginterconnecting cavities in the base portions thereof to form an annularchamber which cooperates with inlet and outlet ports disposed adjacentthe trailing edges of these blades and adjacent the casing and rotorrespectively to remove water and steam from the stationary blades, toseparate the water and steam, and to direct the steam toward an adjacentrow of rotating blades and the water to a drain.

'8 Claims, 2 Drawing Figures MOISTURE REMOVAL DEVICE FOR A STEAM TURBINEBACKGROUND OF THE INVENTION Since the tips of the leading edges of lowpressure rotating blades are theprirnary erosion areas, it is a commonpractice to coator form the tips of these, blades with a hard erosionresistant material, such as Stellite. However, providing the erosionresistant lead-- encircling the rotor 3, an annular array ofcircumferentially spaced rotatable blades 7 fastened to the rotor 3, anannular array of circumferentially spaced stationary blades or nozzles 9fastened to the casing and a device 11 disposed in the stationary blades9 for removing water and steam from the motive steam as the water passesover the stationary blades, separating the steam from the water,returning the steam to perform additional work on the rotating blades 7and directing the water to a drain 12.

Motive steam flows through the blades 7 and 9 from left to right, asshown in the drawings, and the blades 7 and 9 have a general air foilshaped cross section with the leading edges 13 and 14 on the left andthe trailing edges 15 and 16 on the right.

As shown in FIG. 1, the device 11 comprises an inlet or first port 17disposed adjacent the casing 5 and trailing edge 15 of the stationaryblades 9, an outlet or second port 19 disposed adjacent the rotor 3 andtrailing edge 15 of the stationary blade 9, and a chamber 21 ing edge onthe rotating blades is expensive and may and the stationary blades .willincrease the velocity of the water droplets and reduce the impactvelocity of the water droplets as they impinge on the rotating blades toreduce erosion. However, this increases the turbine length, weight, andcost.

SUMMARY OF THE INVENTION In general, a turbine operated by motive steam,when made in accordance withthis invention, has a rotor, a casingencircling the rotor, an annular array of circumferentially spacedrotatable blades, an annular array of 'circumferentially spacedstationary blades, a condensate drain and a device disposed in thestationary blades for removing water and steam from the motive placed incommunication with the ports 17 and 19 by steam, separating the steamand water, returning the steam to perform additional work on therotating blades, and directing the water to the drain.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERREDEMBODIMENTS Referring now to the drawings in detail, FIGS. and 2 show asteam turbine 1 having a rotor 3, a casing 5 respectively, The ducts 23and 25 terminate in the chamber 21' and have short nozzles 27 and 29,respectively, which extend into the chamber 21 to prevent reentrainmentof the water and steam which separate due to a reduction in the velocityof the mixture entering the chamber 21. Water separated from the mixtureflows by gravity to the drain 12 and moisture-free steam flows to theoutlet port 19 as a result of the difference in pressure between theinlet and outlet ports 17 and 19, resulting from their respectivelocations and the higher pressures which are created adjacent the casingdue to the centrifugal forces acting on the motive steam. The sameforces cause the moisture or water in the steam to be spun outwardlytoward the cas- The arrangement of the ducts 23 and 25 shown in FIG. 1is such that there will be essentially no reentrainment of waterdroplets in the steam flowing through the discharge duct 25 irrespectiveof the radial orientation of the stationary blades.

The annular chamber 21 is formed from interconriecting, registeringcavities 29 in the base portions of the stationary blades 9. Ifrequired, peripheral seals or gaskets may be disposed between adjacentbase portions to form a seal around the cavity to produce the annularsealed chamber 21.

FIG. 2 shows a modification, wherein the annular chamber 21 has an outercompartment 31 and an inner compartment 33. The inlet port 17 is broughtinto direct communication with the outer compartment 31 by the inletduct 23 and the outlet port 19 is brought in direct communication withthe inner compartment 33 by the outlet duct 25. Walls 35, separating theinner compartment 33 from the outer compartment 31, have a plurality ofopening 37, which allow steam to flow freely from the outer to the innercompartment. The outer compartment 31 has a larger volume than the innercompartment 33, so as to allow the steam and water mixture enteringthrough the inlet ports 17 and ducts 23 to slow down so that the waterseparates from the steam. The water then flows by gravity to the drain12, while the steam flows into the inner compartment 33 and out theoutlet ducts 25 and ports 19. The inlet and outlet ducts 17 and 19 maybe disposed to cooperate with the inner and outer compartments 31 and 33to foster centrifugal separation of the mixture of steam and water andthereby effectuate more complete separation.

The stationary blades with cooperatively associated chambers, ports, andducts, hereinbefore described advantageously extract some steam with themoisture, which greatly enhances the effectiveness of the moistureremoval from the blades and by separating the moisture from the steamand returning the steam to the main steam flow to perform additionalwork on the downstream rotating blade provides optimum moisture removalwith a minimum loss of motive steam.

What is claimed is:

1. A turbine operated by motive steam and having a rotor, a casingencircling said rotor, an annular array of circumferentially spacedrotatable blades, an annular array of circumferentially spacedstationary blades, a condensate drain, and means disposed in saidstationary blades for removing water and steam from the motive steam,separating the steam and water, returning the steam to performadditional work on the rotatable blades, and directing the water to thedrain.

2. A turbine as set forth in claim 1, wherein the blades have a generalair foil shaped cross section with leading and trailing edges and theremoval and separating means comprises a first port disposed adjacentthe trailing edge of the stationary blade and the casing, a second portdisposed adjacent the rotor, and a chamber in communication with saidports, said chamber being sufficiently large to reduce the velocity ofthe steam and water mixture entering through the first port to causeseparation thereof and the second port being disposed to allow steam toflow from said chamber to rejoin the motive steam.

3. A turbine as set forth in claim 2, wherein the second port isdisposed adjacent the trailing edge of the stationary blade.

4. A turbine as set forth in claim 2, wherein interconnecting cavitiesin the stationary blades register to form the chamber.

5. A turbine as set forth in claim 2, wherein the first portcommunicates with said chamber through a first duct and. the second portcommunicates with said chamber through a second duct and said first andsecond ducts are so disposed with respect to the chamber that theycooperate with the chamber to provide separation of water and steamirrespective of the radial orientation of the stationary blades.

6. A turbine as set forth in claim 2, wherein the chamber comprises aninner compartment and an outer compartment there being a variety ofopenings between said compartments and the first port is in directcommunication with said outer compartment and the second port is indirect communication with the inner compartment.

7. A turbine as set forth in claim 5, wherein the inner compartmentsregister to form an inner annular chamber and the outer compartmentsregister to form an outer annular chamber containing said inner annularchamber.

8. A turbine as set forth in claim 7, wherein the volume of the innerannular chamber is less than the volume of the outer annular chamber.

at a: 4 a t

1. A turbine operated by motive steam and having a rotor, a casingencircling said rotor, an annular array of circumferentially spacedrotatable blades, an annular array of circumferentially spacedstationary blades, a condensate drain, and means disposed in saidstationary blades for removing water and steam from the motive steam,separating the steam and water, returning the steam to performadditional work on the rotatable blades, and directing the water to thedrain.
 2. A turbine as set forth in claim 1, wherein the blades have ageneral air foil shaped cross section with leading and trailing edgesand the removal and separating means comprises a first port disposedadjacent the trailing edge of the stationary blade and the casing, asecond port disposed adjacent the rotor, and a chamber in communicationwith said ports, said chamber being sufficiently large to reduce thevelocity of the steam and water mixture entering through the first portto cause separation thereof and the second port being disposed to allowsteam to flow from said chamber to rejoin the motive steam.
 3. A turbineas set forth in claim 2, wherein the second port is disposed adjacentthe trailing edge of the stationary blade.
 4. A turbine as set forth inclaim 2, wherein interconnecting cavities in the stationary bladesregister to form the chamber.
 5. A turbine as set forth in claim 2,wherein the first port communicates with said chamber through a firstduct and the second port communicates with said chamber through a secondduct and said first and second ducts are so disposed with respect to thechamber that they cooperate with the chamber to provide separation ofwater and steam irrespective of the radial orientation of the stationaryblades.
 6. A turbine as set forth in claim 2, wherein the chambercomprises an inner compartment and an outer compartment there being avariety of openings between said compartments and the first port is indirect communication with said outer compartment and the second port isin direct communication with the inner compartment.
 7. A turbine as setforth in claim 5, wherein the inner compartments register to form aninner annular chamber and the outer compartments register to form anouter annular chamber containing said inner annular chamber.
 8. Aturbine as set forth in claim 7, wherein the volume of the inner annularchamber is less than the volume of the outer annular chamber.